1. Field of the Invention
The present invention generally relates to a network system for interworking a Wireless Local Area Network (W-LAN) and a 3rd-Generation (3G) mobile communication network, and in particular, to a network system for interworking a W-LAN and a 3G mobile communication network through a Radio-over-Fiber (RoF) link.
2. Description of the Related Art
The recent activation of wireless Internet services and W-LANs has made interworking a 3G mobile communication network and a W-LAN more appealing to service providers and mobile users.
Interworking a W-LAN and a 3G system is appealing to service providers and mobile users because it combines two highly desirable features into one network system. W-LAN service by itself provides high transmission speed, but it has narrow service coverage and limited mobility. Although having wide service coverage and guaranteeing mobility, a 3G (CDMA-2000 or UMTS) service by itself has lower data transmission speed and is more expensive than the W-LAN service. For these reasons, interworking a W-LAN system and a 3G system has significance in that it creates customer satisfaction and market opportunities by utilizing advantages inherent in the W-LAN system and the 3G system.
Interworking systems can be a tightly coupled system or a loosely coupled system. In the tightly coupled system, functions such as authentication are implemented by the 3G system. In the loosely coupled system, functions such as authentication are implemented by both the 3G system and the W-LAN system.
FIG. 1 illustrates a conventional tightly coupled network interworking a W-LAN system and a 3G system. As illustrated in FIG. 1, in the conventional tightly coupled network, a W-LAN system 300 is connected to a remote network 400 for packet communication and a 3G core network 100 having communication networks 104, 105, and 106.
The 3G core network 100 which is connected to the Internet 200 is linked with the remote network 400 and the W-LAN system 300 through a Packet Data Service Node (PDSN) 103 wherein Internet Protocol (IP) is utilized to connect to a packet communication network.
The remote network 400 includes Base Transceiver Stations (BTSs) 111-1 and 111-2 for connection with a Mobile Station (MS) 112, a Base Station Controller (BSC) 110 for managing the BTSs 111-1 and 111-2, and a Packet Control Function (PCF) 109 for performing a buffering function and managing the state of the MS 112 in data transmission from and to a Packet Data Service Node (PDSN).
The remote network 400 is connected to a Home Location Register (HLR) 106 through a Mobile Switching Center (MSC) 104 and the PSTN 105.
The W-LAN system 300 is connected to the PDSN 103 and the 3G core network 100 and includes an Access Controller (AC) 107 for managing Access Points (APs) and a plurality of APs 108-1, 108-2, and 108-3 for connection with a W-LAN terminal 113 for W-LAN service.
As illustrated in FIG. 1, in the tightly coupled system, the W-LAN system 300 is connected to the 3G core network 100 and the W-LAN system 300 operates as a part of a 3G network. MS 112 and the W-LAN terminal 113 use a 3G service through the remote network 400 of a 3G system or the W-LAN system 300 according to a network connection environment. Thus, interworking of a 3G network and a network of the W-LAN system 300, requires separate interworking equipment where basic service control and management function is performed by the 3G network. In other words, the 3G core network 100 includes a Home Agent (HA) 102 for position management and an Authentication, Authorization, and Accounting (AAA) server 101 for authentication.
FIG. 2 illustrates a conventional loosely coupled network interworking a W-LAN system and a 3G system. As illustrated in FIG. 2, in the conventional loosely coupled network, authentication is independently preformed by a remote network 400 for packet communication, a 3G core network 100 having communication networks 204, 205, and 206, and a W-LAN system 300.
The 3G core network 100 which is connected to the Internet 200 is linked with the remote network 400 and the W-LAN system 300 through a PDSN 203 wherein Internet Protocol (IP) is utilized to connect to a packet communication network.
The remote network 400 includes BTSs 212-1 and 212-2 for connection with an MS 214, a BSC 211 for managing Base Transceiver Stations (BTSs) 212-1 and 212-2, and a PCF 210 for performing a buffering function and managing the state of the MS 214 in data transmission from and to the PDSN 203.
The remote network 400 is connected to a HLR 206 through an MSC 204 and a PSTN 205.
The W-LAN system 300 is connected to the PDSN 203 and the 3G core network 100 and includes an AC 207 for managing APs, a plurality of APs 209-1, 209-2, and 209-3 for connection with a W-LAN terminal 213 for a W-LAN service, and an AAA server 208 for authentication of the W-LAN system 300.
As illustrated in FIG. 2, in the loosely coupled system, the 3G core network 100 and the W-LAN system 300 independently operate. Interworking is performed such that 3G networks 100 and 400 and the W-LAN system 300 operate independently but interface information for interworking related to billing and authentication is transmitted to AAA servers 201 and 208 included in the 3G networks 100 and 400 and the W-LAN system 300.
As described above, a conventional network interworking a W-LAN system and a 3G system is divided into a tightly coupled network and a loosely coupled network. The tightly coupled network has an advantage in that it has the added functions of a conventional 3G system, related to security, authentication, and billing, which can be applied to a W-LAN system. However, modules related to interworking with the 3G system need to be mounted in a W-LAN terminal and the time and cost required for standardization increase. As a result, the cost of a subscriber service increases and the load on existing 3G networks may increase since a W-LAN system uses an existing 3G core by sharing a 3G core network, resulting in instability of an existing 3G network system.
On the other hand, a loosely coupled system does not increase the load on 3G networks due to interworking because it uses independent networks. However, since advanced functions such as a position control, a Quality of Service (QoS), and security defined in a 3G network are not supported in a W-LAN system, there exist authentication and security problems in a W-LAN area.
Therefore, a system providing more efficient interworking of a 3G mobile communication network and a W-LAN system is required.